Joseph zubaty



.1. zu BATY 1,783,932

AMMETER Filed Feb. 6, 1929 Patented Dec. 2, 1930 UNITED STATES PATENT OFFICE JOSEPH ZUBATY, OF FLINT, MICHIGAN, ASSIGNOR TO A C SPARK PLUG COMPANYf F FLINT, MICHIGAN, A COMPANY OF MICHIGAN AMMETER Application led February 6, 1929. Serial No. 837,904.

This invention relates to ammeters and is particularly concerned with improvements in the armature and its inter-relation with the field piece.

In existing ammeters using a horseshoe magnet, the field piece is usually placed between the poles of the magnet so that its longitudinal or longest axis is in alignment with the magnetic lines of force. The purpose of this field piece is to concentrate the flux between the poles so as to produce a better effect upon the armature pivoted adjacent the field piece. In the past, it has been customary to provide fingers or projecting ends on the field piece to extend toward the armature so as to produce a greater and more uniform field intensity about the armature and thereby bring about a more accurate swing of the armature and reading on the dial. In structures of this kind as the armature swung away from its normal position it tended to get further away from the projecting portions of the field piece and thus increased the air gap between the armature ends and the field piece and magnct, and thereby increased the liability of error or inaccuracy and necessitated the use of a non-uniformly graduated dial.

In the present invention it is possible to use a uniformly graduated dial byconstructing the armature with ends which project closer into the field of the magnet and by positioning the field piece so that its narrow portion is transverse to the magnetic field, or in other words the longer portion of the field piece is positioned transverse to the magnetic lines of force. The frame on which the mechanism is mounted is provided with suitable slots to receive the bent ends to the armature so that they may swing without interference with the frame.

An armature provided with bent or projecting ends as stated will be able to receive a greater number ofthe lines of force due to its closer proximity to the magnetic field and as it swings from its normal position the lines of force between the poles of the magnet will tend to pass through the projecting ends rather than through the air gap, following of course the lines of least resistance. This will enable a more accurate reading to be obtained and also permit of the use of a uniformly graduated dial.

On the drawing:

Figure 1 is a View of the front of the ammeter.

Figure 2 is a section on the line 2-2 of Figure l.

Figure 3 is a plan view of the mechanism with the dial removed.

Figure 4 is a vicw of the gage mechanism looking into the gage from the looped end of the horseshoe magnet with parts shown in section for purposes of clearer illustration.

Figure 5 is a view of the mechanism of Figure 4 looking thereinto from the side of the magnet.

Figure 6 is a detailed diagrammatic plan View showing the path taken by the lines of force when the armature is swung from its normal position.

Figure 7 is an enlarged sectional detail of the armature and field piece with their interrelated parts.

Referring to the drawing the numeral 2 indicates an ammeter as a whole, provided with the dial 4 having a uniformly graduated scale 6 over which the pointer 8 swings. The dial is provided with the arcuate slot 10 to allow for the pointer to extend from the interior of the ammeter over the dial.

The ammeter is provided with the usual case 12 in which there is secured the frame 14 which also acts as a conductor. The frame includes the feet 16 secured to the' casing bottom by means of the headed terminal bolts 18 and the nut 20, suitable insulating material 22 being provided to insulate the terminals from the case. The frame also includes the feet or upright portions 24 and the bridge or shelf 26. The bridge includes the hook shaped underlapping portion 28 and which forms a mounting for the shaft 30 suitably pivoted between the hook portion 28 and the bridge 26. The pointer 8 is mounted on the shaft 30 and an armature 32 is also secured to the shaft immediately above the pointer. Suitable washer like members 34 are secured to the shaft 30 to hold the pointer and armature in position.

Thearmature 32 has the bent ends 36 which project upwardly through arcuate slots 38 in the bridge piece 26 of the frame 14. The purpose of these slots is to permit the armature ends 36 to swing with relation to the frame and also to cause them to project upwardly between the poles 40 of the horseshoe magnet 42. The horseshoe magnet is suitably mounted at its ends in notches or cut-out portions 44 at the edge of the legs 24 and tongues 46 are provided at the side of the bridge piece and are bent under both poles 40.

A field piece 48 is secured to the upper portion of the bridge 26 between but slightly above the poles 40 of the magnet 42. By rei ferring to Figures 3, 4 and 7, it will be seen that the field piece 48 is positioned with its longitudinal axis at right angles to the line joining the poles or it is positioned so that its narrowest part is transverse to the lines of force between the poles. The field piece has the usual function of concentrating the lines of force between the magnetic poles. This is better illustrated in Figure 6.

By referring to Figure 6 (in which the arrows indicate the direction of the electric current), it will be seen that the armature is shown at substantially one of its extreme positions and the direction taken by the magnetic lines of force between the two poles is indicated in dotted lines at A. Due to the fact that the bent ends 36 of the armature extend directly up between the poles or into the magnetic field, the lines of force will tend to pass through the armature or in the direction indicated by the dotted lines, and will thereby exert a greater force o`r have a greater effect on the armature and enable more accurate calibration and reading of the pointer on the dial. The armature therefore acts as a shunt for the flux lines of the magnet, taking the flux away from the field piece. As the armature swings away from its normal position the bent ends 36 will have the advantage over an armature without the bent ends in that the bent portions will serve to better concentrate the lines of force through the armature. As the air gap increases there will be less tendency for error in an armature as shown in the invention when compared to a fiat armature.

The dial 4 is suitably mounted on lugs 50 formed integral with the bridge piece 26.

The pointer is providedwith a counter bal ancing end portion 52 which is considerably wider than the main portion so that the pointer will be balanced with reference to the axis of the shaft 30.

I claim:

1. In an ammeter, a frame, a magnet, an armature rotatably mounted in said frame, a pointer mounted to swing with said armat-ure, a field plate between the poles of the magnet with its longitudinal axis transverse to the lines of force, and bent ends on said a pointer mounted to swing withsaid arma- A ture, a field piece positioned between the poles of the magnet with its longitudinal axis transverse to the lines of force, angularly projecting ends on Saidarmature extending on opposite sides of said field piece, y

and slots in said frame in which said ends operate.

3. In an ammeter, a frame, a magnet secured to said frame, an armature rotatably mounted in said frame, a pointer mounted to move with said armature, a field piece secured to said frame between the poles of the magnet, and angularly disposed ends on said armature extending on opposite sides of said field piece.

4. In an ammeter, a frame, a magnet secured to said frame, an armature rotatably mounted in said frame, a pointer mounted to move with said armature, a field piece secured to said frame between the poles of said magnet, angularly disposed ends on said armature extending on opposite sides of said field piece, and slots in said frame in which said ends operate.

5. In an alnmeter, a frame, a magnet, an armature rotatably mounted in said frame, a pointer mounted to move with said armature, a field piece secured to said frame between the poles of the magnet, said frame extending between said armature and field piece, angularly disposed ends on said armature, and slots in said frame in which said ends operate.

6. In an ammeter, a frame, a magnet, an armature rotatably mounted in said frame, a pointer mounted to move with said armature, a field piece secured to said frame between the poles of the magnet, slots in said frame between said field piece and poles, and angularly disposed ends on said armature operating in said slots.

7. In an ammeter, a frame, a bridge on said frame, a magnet mounted on said bridge, an armature rotatably mounted in said frame, a pointer mounted to swing with said armature, and a field piece mounted on said bridge between the poles of the magntt to concentrate the lines of force adjacent the armature.

8. In an ammeter, a frame, a bridge on said frame, a magnet mounted on said bridge, an armature rotatably mounted in said frame, a pointer mounted to swing with said armature, and a field piece mounted on said bridge between the poles of the magnet and having its longitudinal axis transverse to the lines of force to concentrate the field adjacent the armature.

9. In an ammeter, a frame, a bridge on said frame, a magnet mounted on said lll bridge, an armature rotatably mounted in said frame, angularly bent ends 0n said armature operating in slots in said bridge, a pointer mounted to swing with said armature, and a field piece mounted on said bridge between the poles of the magnet to concentrate the lines of force adjacent the amature.

In testimon)7 whereof I aflx my signature.

JOSEPH ZUBATY. 

